Page 1 of 2 12 LastLast
Results 1 to 40 of 68

Thread: Robertson STOL

  1. #1
    danfena's Avatar
    Join Date
    Apr 2007
    Location
    Northern MN
    Posts
    88
    Post Thanks / Like

    Robertson STOL

    Anyone have any used jawcranks and belcranks? I want to make my experimental c175TD droop the ailerons.
    Any other way to do this? Thinking of a sliding belcrank?
    I have a diagram of the Robertson, but it would be difficult to copy without having one.
    Sierra wont sell just the parts.

  2. #2

    Join Date
    Apr 2003
    Location
    Clearwater,Fl
    Posts
    2,474
    Post Thanks / Like
    Bone Yards? White Industries, Atlanta Salvage, Wentworth, Suprise Valley Aviation, just to name a few. Somebody has had to have wrecked one.
    Last edited by Fortysix12; 01-27-2011 at 09:00 PM.

  3. #3
    danfena's Avatar
    Join Date
    Apr 2007
    Location
    Northern MN
    Posts
    88
    Post Thanks / Like
    Thanks,
    I did surch at a few of these on line, but I think I will need burn up the phone lines.
    DF

  4. #4

    Join Date
    Apr 2003
    Location
    Clearwater,Fl
    Posts
    2,474
    Post Thanks / Like
    Another angle might be to find out who back in the day or presently installs the system, or somebody who know's where one is. Phone is the best way for something like this. Insurance salvages, smaller bone yards, the mechanic who's an expert on rigging and repairing them. Lot's of angles. Ask ask and ask some more. You find what you're looking for. There used to be company in florida all they did is look for used part for people. Forget there name or if they are even in business.

  5. #5
    Aussie Scout's Avatar
    Join Date
    Aug 2010
    Location
    Tasmania Au
    Posts
    87
    Post Thanks / Like
    I operated a C185 seaplane with a Robinson stol kit fitted and it was awful. The ailerons lost authority below 80 knots and the general handling was way behind a standard 185 seaplane. The owner of the plane eventually removed the kit entirely and the transformation back to a great aeroplane was astounding. It went from a dog no one wanted to fly to a great ride!
    Perhaps the kit may be better on wheel plane but the seaplane would not pull the angle of attack required for this mod to shorten the take off run.
    This kit may well be kicking around a hanger over here, PM me if you want the owners contact.
    Last edited by Aussie Scout; 01-28-2011 at 09:45 PM.

  6. #6
    danfena's Avatar
    Join Date
    Apr 2007
    Location
    Northern MN
    Posts
    88
    Post Thanks / Like
    Thanks, I will PM you. Sorry to here of your less than satifactory result. I still want to try it. What part of Au are you in? Au is on my bucket list of places to visit.

  7. #7
    mvivion's Avatar
    Join Date
    Jun 2003
    Location
    Crookston, MN
    Posts
    7,850
    Post Thanks / Like
    Quote Originally Posted by Aussie Scout View Post
    I operated a C185 seaplane with a Robinson stol kit fitted and it was awful. The ailerons lost authority below 80 knots and the general handling was way behind a standard 185 seaplane. The owner of the plane eventually removed the kit entirely and the transformation back to a great aeroplane was astounding. It went from a dog no one wanted to fly to a great ride!
    Perhaps the kit may be better on wheel plane but the seaplane would not pull the angle of attack required for this mod to shorten the take off run.
    This kit may well be kicking around a hanger over here, PM me if you want the owners contact.
    Every set of floats/airplane/configuration requires that one learn to adapt to it. I've flown a good bit in float equipped, Robertson modified Cessnas, and I love them.

    You hear a lot of people complaining about the RSTOL airplanes, and there are some different characteristics you must adapt to, but they work fine, and angle of attack on takeoff on floats was never an issue on any of the several that I've flown. One of the airplanes I flew suffered a crankshaft failure and subsequent ugly landing in mountainous terrain. When we replaced that airplane, I specifically asked for an RSTOL modified airplane. Angle of attack for takeoff on floats is limited by the floats, generally. And, there are other ways to get underway short if you have long floats.

    MTV

  8. #8

    Join Date
    Apr 2003
    Location
    Clearwater,Fl
    Posts
    2,474
    Post Thanks / Like
    Robertson STOL changes the mission of the airplane. I've flown a Robertson STOL 400 Comanche for 16 years. With regards to the 400, it reduced the stall speed from 78 to 61 mph. It increased the operating range. It added 200 pounds to the usefull load. 400 ft takeoff and landing are routine. It changed the flight characteristics to that of a C182. I like it. The mod is not for a conservative pilot. As Mike has stated, you must be willing to trane using the airplane, its' not the same airplane,it's a new airplane which requires retraning. I pushed myself to find the boundries,within reason of coarse. But I heard the same argument discrediting the C185 RSTOL on floats, which makes me wonder if it's really true, this was from a Montana operator.
    Last edited by Fortysix12; 01-30-2011 at 04:23 PM.

  9. #9
    skywagon8a's Avatar
    Join Date
    Mar 2008
    Location
    SE Mass
    Posts
    3,589
    Post Thanks / Like
    I am a big fan of drooping ailerons. I noticed a stall speed reduction of 6-8 mph. Keep their control separate from the flaps, which is the Robertson's downfall. There are times when this will be very helpful. It is best not to use them in crosswinds as the up aileron looses it's effectiveness and the stall speed of the down aileron is a little higher. With the wind on the nose it gives the effect of increasing the angle of incidence of the whole wing. The total travel remains the same. It is the neutral point which is moved. The system in my 185 is electric powered by a 172 flap motor. It was STCd on both the 185 and 172. I purchased the plans and permission from the STC holder and built my own parts. The STC is limited to "takeoff use only" as it does make the plane more nose heavy during landings by increasing the lift at the trailing edge of the wing.
    N1PA

  10. #10
    Dave Calkins's Avatar
    Join Date
    Jul 2002
    Location
    Anchorage, Alaska
    Posts
    4,685
    Post Thanks / Like
    We've been through the RSTOL discussion lots. Some guys like 'em, some don't.

    I do. Very obvious performance increases that are documented by FAA flight test.

    Also, there is an Interior Alaskan operator whose 185's and 206's all have RSTOL. He simply canNOT work his LZ's with a stock airplane.

    I always have to wonder who rigged the RSTOL or what is wrong with the airplane when a pilot denegrates the kit. The short field/slow flight performance increase is so obvious on these RSTOL airplanes, floats or wheels.

    I don't want to argue, I want to fix your crappy airplane that happens to have an RSTOL! DAVE

  11. #11
    Aussie Scout's Avatar
    Join Date
    Aug 2010
    Location
    Tasmania Au
    Posts
    87
    Post Thanks / Like
    Interesting points. It was not my airplane and I had no say in the removal of the kit but it just wasn't necessary for the operation in question, which is a tourist op to a single destination. Also in this op pilots come and go, most only hang around a season or two then move on to other things. I think the RSTOL is more for the owner pilot who can explore the envelope than it is a kit for a commercial operations that have a heap of different pilots. This plane was ex US with the kit already fitted. Removing the kit was a serious undertaking and I am sure the owner did not make the decision lightly. Hopefully the parts are a plus for someone out there.
    Rob: Tasmania, Australia
    www.tasmanenergy.com.au

  12. #12

    Join Date
    Dec 2004
    Location
    Homer, Alaska
    Posts
    525
    Post Thanks / Like

  13. #13
    Aussie Scout's Avatar
    Join Date
    Aug 2010
    Location
    Tasmania Au
    Posts
    87
    Post Thanks / Like
    Interesting investigation and very detailed. The Finnish Aviation Investigation Bureau left little to chance with this report. The Aussie equivilant would only be a couple of pages for a single fatality accident in a GA aircraft. Probabaly just as well with our penchant for passing on the cost of everything to the user.
    Rob: Tasmania, Australia
    www.tasmanenergy.com.au

  14. #14
    danfena's Avatar
    Join Date
    Apr 2007
    Location
    Northern MN
    Posts
    88
    Post Thanks / Like
    Thanks for all the good input. You gotta love Supercub.org

  15. #15
    nanook's Avatar
    Join Date
    Aug 2002
    Location
    northern alaska
    Posts
    974
    Post Thanks / Like
    Robertson STOL sucks.....worst crosswind landing characteristics....go with the leading edge cuff and a clean aileron (not drooped) I can't believe that anyone would recommend this crappy set-up....decreased aileron effectiveness(travel)....combined with boundary layer separation at the aileron leading edge.......

  16. #16
    mvivion's Avatar
    Join Date
    Jun 2003
    Location
    Crookston, MN
    Posts
    7,850
    Post Thanks / Like
    Anyone who briefly checks out that Finnish report on the accident should actually READ the accident report. It was noted that the pilot simply trimmed the aircraft for takeoff, and allowed it to climb without further input by the pilot. He had never actually stalled the airplane, and like the pilot of the Colgan Air Dash 8 accident in Buffalo, he didn't recognize the stall warning for what it was.

    The Finnish government put an RSTOL airplane through a LOT (as in a couple hundred) stalls, and eventually managed to get one to roll off.......duh. I'd bet that with a few hundred tries, we could get a LOT of airplanes to roll off in a stall. The Finnish accident report accurately placed the blame for the accident on the pilot, but then went off on a tangent trying to demonstrate the "dangerous" flight characteristics of this modification. Anyone who's flown an RSTOL airplane and done aggressive stalls will tell you that if you push them hard, occassionally they'll roll off hard. Big deal--don't be stupid.

    I'm with Dave on this one....we hear all these experts on RSTOL airplanes, and others, and yet those airplanes are out there, working, every day. I put a lot of hours on RSTOL equipped airplanes and, if I were to do the same kind of work again (almost exclusively off airport) I'd want an RSTOL airplane again

    Do RSTOL equipped airplanes have less aileron authority AT CERTAIN FLAP SETTINGS? Certainly. So, in certain, very limited circumstances, you may have to say no to a landing or a takeoff. Or maybe learn what flap settings minimize this effect. On the other hand, EVERY time you takeoff or land or maneuver at slow speed, an RSTOL Cessna 185s stall speed will be FOURTEEN knots lower than a stock wing airplane. And that is documented by full FAA flight test program, NOT an advertising claim, like we see for many other mods. The RSTOL mods do significantly reduce stall speed....far more so than any other so called STOL modification I've seen.

    There are a lot of ways to use that capability, folks. Go get some time in one, learn to fly it, actually WORK it, and learn it's characteristics, both negative and positive and I think most folks conclude that the positives far out shine the minor limits on aileron effectiveness.

    And, A simple, inexpensive modification to the RSTOL airplanes greatly restores the aileron effectiveness in RSTOL airplanes: Aileron gap seals. Easy to install and pretty cheap.

    Finally, a lot of Cub pilots have discovered that the Super Cub has pretty limited aileron effectiveness at slow speeds. The Vortex Generator kits that have gained so much popularity with the Cub crowd REALLY improve aileron effectiveness in the Cub at slow speeds as well. Fly a Cub with VGs for a good while, then go back to a straight wing Cub, and the difference is noticeable. But, again, it's just a characteristic that the PILOT must learn to compensate for.

    Oh, and by the way, many deHavilland Canada products, such as the Beaver, Otter, etc also droop their ailerons with flap deflection......I guess they're dangerous as well..

    MTV
    Last edited by mvivion; 01-30-2011 at 10:12 AM.

  17. #17
    nanook's Avatar
    Join Date
    Aug 2002
    Location
    northern alaska
    Posts
    974
    Post Thanks / Like
    There are much better STOL systems out there than Robertson....end of story....move on ....get over it....
    Mike: Those of us who actually worked our airplanes, got paid by the hour or the trip...We fly/flew in very tough conditions for years on-end and we are still here to discuss our experiences....most of the Government pilots parked their airplanes when the weather got tough and still collected their salary....so mister retired gov. pilot, don't talk to me about working an airplane....(you sound like a real dumb ass, when you talk down to people).. I'm still up here (humbly)working my airplanes in Alaska.....
    Last edited by nanook; 01-30-2011 at 11:16 AM.

  18. #18
    Dave Calkins's Avatar
    Join Date
    Jul 2002
    Location
    Anchorage, Alaska
    Posts
    4,685
    Post Thanks / Like
    No certified "STOL" kit gives short/slow takeoff and landing performance equal to the RSTOL.

    If you only have one airplane and do lots of crosswind stuff, it may not be for you.

    However, as I said above, there's a guy who puts RSTOL on all his 185's and 206's because stock 185's and 206's won't do the job...period...

  19. #19
    mvivion's Avatar
    Join Date
    Jun 2003
    Location
    Crookston, MN
    Posts
    7,850
    Post Thanks / Like
    Nanook,

    Sorry, I did not intend to sound like I was talking down to people. If it came across that way, please accept my apology.

    There is a "He said, she said" aspect often found on internet forums, though. In my experience, that frequently raises it's head in discussions of the Robertson equipped airplanes. I can't tell you how many people I've had go on at great length about how dangerous the RSTOL airplanes are until you ask them specifically how much actual flight experience they have in those airplanes. More often than not, the subject gets changed really fast. And that's true with a lot of other things as well. Lots of "experts" out there. I was simply making the point that I do have experience in RSTOL equipped airplanes.

    As to your personal attack on me: you're right--I worked for the government. So, what's your point? I've flown in some pretty ugly weather (I worked in Kodiak for eight years), but what does flying in bad weather have to do with RSTOL equipped airplanes? Now, there are 135 guys who do a lot of off airport stuff as well. And, some of them operate RSTOL airplanes, by the way. Again, what's your point? Whether you believe it or not, I have worked airplanes. Apparently nowhere near as much as you have....again, what is your point?

    I don't see where personal attacks on me or government employed pilots in general has anything to do with the safety or operability of RSTOL equipped airplanes. But, again, this is generally the way these discussions of Robertson STOL equipped airplanes seem to go--personal attacks and he said, she said.

    So, attack away. I still like Robertson equipped airplanes, and you have every right to your opinion, both of the airplanes and of me.

    MTV

  20. #20
    nanook's Avatar
    Join Date
    Aug 2002
    Location
    northern alaska
    Posts
    974
    Post Thanks / Like
    Well MTV, apology accepted...The Gov. pilot cracks are a cheap shot....Maybe a deep rooted jealousy over the fact that I had to fly to pay the bills and you guys could sit in camp and still get paid....Anyway, I know quite a few Gov. pilots up here (Alaska) and have nothing but respect for their abilities.....
    I have on many occasions had to deal with the crosswind limitations of the Robertsons STOL...I would not put it lightly...I would and do consider it to be a major design flaw....Also the Cessna 100 and 200 series aileron attach system was not designed to droop.(obviously)... You will find the aft hanger attach brackets cracked at the lower skin 90 degree point...(you might want to look at those if you have RSTOL)....Also drooping an aileron to increase the wing camber/cord thus lift, should be done by NOT disturbing the boundary layer with the aileron leading edge. The aileron hinge point should drop lower ( in some cases also aft) when drooped to avoid disturbing the air flow while increasing lift. The RSTOL is a poor design in that regard. Long story short....You really need to design the wing aileron attach points to droop, not just droop the aileron....

  21. #21
    Dave Calkins's Avatar
    Join Date
    Jul 2002
    Location
    Anchorage, Alaska
    Posts
    4,685
    Post Thanks / Like
    A comment specific to the "gov't pilots":

    As far as the State Troopers, aren't they "troopers first" and then pilots?

    Trooper Cub............I cannot escape the vision of a low-time/minimal-real-experience driver flying an overweight Cub that was spec'd by a guy at a desk.

    I have the same vision of the OAS guys, the CAP guys, etc. etc.

    I've seen some GOOFY antics from representatives of each of these "agencies"

    I would love for you, MTV, or any one else to straighten me out on my perception. Certainly there are quality operators among this group. Thanks. DAVE

  22. #22
    nanook's Avatar
    Join Date
    Aug 2002
    Location
    northern alaska
    Posts
    974
    Post Thanks / Like
    Dave, The Gov. guys that I'm referring to, all came from the "real world", were pilots before they became Gov. pilots...I remember the early nineties on the west coast (AK) when someone somewhere decided, we can train biologist to be pilots. That way we don't have to pay these prima-donna pilots anymore, we can save money...They wrecked eleven airplanes(that I know of) that year....Maybe those pilots aren't so costly after all....Maybe Mike trained some of those biologist/pilots.....sorry Mike, another cheap shot.....

  23. #23
    nanook's Avatar
    Join Date
    Aug 2002
    Location
    northern alaska
    Posts
    974
    Post Thanks / Like
    Now that I think about it....I was flying back to Fairbanks quite a few years ago, when flight service asked me to see if an ELT was going off near Tanana. I was just south of Tanana so I swung up that way and didn't see or hear a thing....I left 121.5 up on a radio and as I neared Fairbanks I started hearing an ELT...I told approach about it and they asked me to fly a vector SE. I flew right over a Husky with it's wheels sticking straight up in the air....It was a Gov. Husky with a newby pilot, being trained how to land on gravel bars. This was MTV's replacement,(after retirement) training his first new guy....
    I have heard from Gov. pilots that I know, that MTV was a good instructor and that they were going to miss him. This incident really drove that home in a hurry....On a side note: the Gov. Pilots had called flight service and passed the message " we are down on the tanana(river) south of Fairbanks, That message got translated to "we are down by Tanana (the village)" 125 miles west of where they were....Give a GPS fix in Latitude/longitude if you want someone to find you...Sorry for the Hijack......

  24. #24
    mvivion's Avatar
    Join Date
    Jun 2003
    Location
    Crookston, MN
    Posts
    7,850
    Post Thanks / Like
    Well, Nanook, you got a couple parts of that Husky deal right....but, the rest of the story: That upside down Husky was indeed my assigned airplane. It was upside down in a really nice, big off airport site, south of FAI, as you described. I really liked that particular spot because it really was pretty large, but it gave folks new to off airport the impression of a confined area, while giving the instructor a little wiggle room.

    The fellow in the front seat of that Husky that day had been in and out of there with me in that airplane the day before at least a half dozen times, and had done so flawlessly, including doing stop and goes in there, as in without turning around. As I said, it was a nice sized site. This fellow was a pretty experienced pilot, but had little or no off airport experience. He had been hired as a PILOT by the NPS. I thought he flew the airplane really well when I flew with him.

    The fellow in the back seat of the Husky the day you described was a relatively high time air taxi pilot who had been hired by NPS. In fact, he wrecked more than a couple airplanes while working for NPS, but always had an excuse. The cause of that accident was him jamming on the brakes right after touchdown, which was right where it needed to be. He then denied having applied the brakes, and had done nothing wrong. I think that was his third govt airplane accident. He then went back to 135 flying, never having done anything wrong in a government airplane

    You know, my recollection of all those accidents that you describe is a little different. In fact, I recall that the vast majority of accidents that occurred within DOI were in fact precipitated by "full time" pilots, not dual function pilots. If you'd like an accounting, accident by accident, I can probably provide same.

    One of my arguments for using dual function pilots was two fold: First, a dual function pilot has some other job to do in January and February when it's too dark and cold to do game surveys, etc. for the most part. Second, while the dual function pilots did participate in a few fender benders-no doubt, the really bad accidents I recall were almost without exception done by a "full time" pilot.

    For example, the last FATAL accident in DOI that involved a dual function pilot in AK was in 1970, in the Brooks Range. But there have been several fatal accidents since then with either a 135 contract pilot or a full time government pilot at the controls.

    I never liked seeing airplanes damaged, but accidents that kill your co-workers just can't be tolerated, and as I said, since 1970, those have all been full time pilots or air taxi pilots, not dual function pilots.

    MTV

  25. #25
    nanook's Avatar
    Join Date
    Aug 2002
    Location
    northern alaska
    Posts
    974
    Post Thanks / Like
    Yea well whatever on the tally of who did what....The end result, the bent metal was the carnage....The new cub, that the biologist pilot wrecked on the Arctic strip South of Kotz. Side loaded and sheared the gear....we never could figure that one out...on that old beach you can land straight into the wind no matter which way...the spit north of kotz. The gal biologist pilot wrecks the 206, gets a boat ride back to the village jumps in the cub, goes back out and wrecks that in the same place....The 185 floatplane flipped over off of the Noatak and on and on......your tax dollars at work....
    Jay wasn't a high time pilot.....
    Last edited by nanook; 01-30-2011 at 06:05 PM.

  26. #26
    Rob's Avatar
    Join Date
    Nov 2002
    Location
    Wellton, AZ
    Posts
    606
    Post Thanks / Like
    I feel for the guy who started this thread just to get parts.... Don't like RSTOL? cool get over it... Like it? cool too... so do I

    danfena, try Beegles in Greeley CO. ONE of the brothers there does not like RSTOL, and successfully convinces a lot of removals...

  27. #27
    nanook's Avatar
    Join Date
    Aug 2002
    Location
    northern alaska
    Posts
    974
    Post Thanks / Like
    The pity starts after you spend the time and money for the RSTOL and then go fly the thing and go s**t what the hell did I do that for!!!!!
    But if you really have your mind made up, I'm sure there are plenty of parts laying around in all the wrecks in Alaska.
    Last edited by nanook; 01-30-2011 at 07:03 PM.

  28. #28
    danfena's Avatar
    Join Date
    Apr 2007
    Location
    Northern MN
    Posts
    88
    Post Thanks / Like
    Hey, nanook. How about rounding me up some parts then, and I'll take my chances.
    thanks.

  29. #29
    nanook's Avatar
    Join Date
    Aug 2002
    Location
    northern alaska
    Posts
    974
    Post Thanks / Like
    What kind you want? We have 185,206,207.....those are the most common wrecked RSTOL up here....Who took over the old George Grant operation at Merrill? They would have some old POS RSTOL parts....

  30. #30
    skywagon8a's Avatar
    Join Date
    Mar 2008
    Location
    SE Mass
    Posts
    3,589
    Post Thanks / Like
    Danfena-This topic has digressed from your search for parts to a rather heated discussion. The discussion has addressed some valid points. Since you are experimental you have a multitude of options. You will find that, when in use, X-wind take off & landings are the downfall of drooping ailerons on Cessnas. That is why I strongly suggest that your drooping system be operated independently of the flaps. Robertson has a direct mechanical link to the flap so that every time that the flaps move, the ailerons move as well. You are not able to not droop the ailerons when the flaps are extended. I think that if the RSTOL airplanes that Nanook operated were set up as I have described that he would have become a big fan. Unfortunately he was the looser.

    You will need to purchase some extra wide ($$$$) piano hinge to replace the hinges. This can be hard to find. The hinge point needs to be moved aft from the false spar in order to get the down travel that is required. This leaves a large gap between the aileron and the top wing skin. This is solved by riveting a strip of aluminum to the wing trailing edge which is wide enough to fill the gap.

    MTV
    I was under the impression that aileron gap seals were part of a Robertson conversion.
    Last edited by skywagon8a; 01-31-2011 at 06:23 AM.
    N1PA

  31. #31
    mvivion's Avatar
    Join Date
    Jun 2003
    Location
    Crookston, MN
    Posts
    7,850
    Post Thanks / Like
    skywagon,

    The gap seals that Robertson provided on some of their kits were not large enough. We found some larger, more effective gap seals somewhere, don't recall where, if I ever actually knew.

    I agree fully that the IDEAL setup would have been to have the aileron droop control separate from the flap control. Wayne Mackey has done that on his airplanes, and that makes a great deal of sense. Best of both worlds.

    I flew two Super Cubs with the old CC drooping aileron modification, and I DID NOT like that setup at all. In fact, we took those kits off those two airplanes, or at least they disabled them.

    Talk about NO aileron authority!

    MTV

  32. #32

    Join Date
    Dec 2008
    Location
    Nova Scotia
    Posts
    679
    Post Thanks / Like
    Dalfena: the owner of one of the best engine overhaul shops in the country was yarning with me when a Robertson 185 took off with a show-off climb. "See that," he said turning to me, "those guys keep me in business."

  33. #33

    Join Date
    Dec 2004
    Location
    Homer, Alaska
    Posts
    525
    Post Thanks / Like
    The Finnish government put an RSTOL airplane through a LOT (as in a couple hundred) stalls, and eventually managed to get one to roll off.......duh. I'd bet that with a few hundred tries, we could get a LOT of airplanes to roll off in a stall.

    Mike, if this is your characterization of the findings of the report, you might want to read it again.


    From the report:

    2.8 Results of the flight tests
    The accident situation was simulated during the test flight so that the indicated air speed was reduced to 40-45 knots with engine on idle power. After this full power was set. When the aircraft accelerated through 50-55 knots the aircraft was pitched up 10 de- grees using the artificial horizon. The aircraft rolled to the right on five attempts from fourteen attempts and rolled 50-70 degrees in two seconds. The simultaneous heading change was 10-20 degrees. The movement would have continued but the incipient spin was recovered. On nine occasions nothing significant happened and the aircraft re- mained under control even at a speed of 40 knots and cross controls.

  34. #34
    mvivion's Avatar
    Join Date
    Jun 2003
    Location
    Crookston, MN
    Posts
    7,850
    Post Thanks / Like
    George,

    They performed a number of stalls. The ones you reference were the FULL POWER stalls. Anyone who stalls one of these airplanes unintentionally while at full power is numb from the waist up, and the guy flying the accident airplane apparently was. Read the entire report. It is simply unbelievable that the Finnish Air agency even bothered to look at the airplane, considering what the pilot told them about the accident sequence.

    Take your 185 out and try some half flap, FULL POWER, FULL stalls, and report back the results. Granted, those are going to be aggressive in the RSTOL airplanes occasionally, but it is my opinion that we still use pilots because they occasionally can use some judgement. I have gotten RSTOL 185's to roll with power on stalls, as well as a lot of other airplanes. This business does require pilot participation.

    MTV

  35. #35

    Join Date
    Dec 2004
    Location
    Homer, Alaska
    Posts
    525
    Post Thanks / Like
    Mike, given the R/STOL supplement procedure, with a rotation speed of 37 knots and an initial climb at 42, wouldn't a full power departure stall be the mostly likely stall to encounter in an R/STOL equipped plane-- especially if the supplement speeds are too slow?

    From the report:

    The R/STOL supplement states also that the STOL take off is done with the flap setting of 30 degrees. The rotation speed is 37 knots and the initial climb speed is 42 knots. The flaps are raised to the setting of 20 degrees after lift off. When the close-in obsta- cles are no longer a factor the speed is increased to 65 knots and flaps are raised.
    The calculations and test flights perfomed during the investigation proved that the STOL take off speeds are slightly too slow and there is a risk of stalling. The wing stalled at a speed of 50-55 knots during the test flights when the angle of attack was rapidly in- creased approximately 10 degrees. It seems to be very important to increase speed near ground or water to over 65 knots before starting to climb. One should not turn dur- ing the initial climb.

  36. #36
    mvivion's Avatar
    Join Date
    Jun 2003
    Location
    Crookston, MN
    Posts
    7,850
    Post Thanks / Like
    George,

    Go fly an RSTOL equipped 185 and try a full power stall. I've done it. It's essentially an aerobatic maneuver, due to nose up pitch attitute, AND the indicated airspeed is BURIED at zero. If you FLY the airplane off as recommended by Robertson, maintaining those speeds, with full power, you've got margin. Remember, the 37 knot stall speed is Vso, power OFF. I'll be the first to admit that a full power stall in an RSTOL 185 is an "interesting" procedure. Then again, the same can be said for many airplanes in a full power stall. Why would you LET the airplane ever get there in a takeoff, though?

    I repeat, you'd have to be numb from the waist up to actually stall one of these things (or a stock 185 for that matter) in a full power climb after takeoff.

    And, in reality, not many of us use the MAXIMUM performance procedures recommended by the manufacturers as a regular practice. How may Cub drivers follow Piper's recommended Vx in a routine climbout after takeoff? That calls for full flaps and 45 mph.

    The guy in Finland used full power, and stalled the airplane on takeoff from a HUGE lake--as in no obstacles....AND he admitted that a) He'd never actually stalled the airplane, and b) he understood the proper procedure for takeoff on floats to be full power, set the trim and keep hands off the controls (That is paraphrasing the report, but essentially, he said he let the airplane climb with pitch). Holy cats is all I could say about that. That accident was EASILY explained and preventable.

    Any airplane will kill you if you push it over into a corner, then keep prodding it until it bites. ANY airplane.

    As an old friend and check airman told me once in the middle of a checkride: "It may be time to do some of that pilot ****".

    MTV

  37. #37

    Join Date
    Dec 2004
    Location
    Homer, Alaska
    Posts
    525
    Post Thanks / Like
    Mike, the reason I posted the link to the report, is I believe anyone flying an R/STOL equipped aircraft, or considering flying one, should, rather than rely on your view of what the R/STOL does to a Skywagon's handling, read the complete report and what they determined in the Finnish investigation. If you read the direct causal factors, while the first is pilot error, neither two nor three is something that R/STOL would likely use in their advertising.

    Direct causal factors
    The investigation commission considered that there were three direct causal factors to the accident:
    The first factor was the incorrect take off procedure used by the pilot. He let the aircraft continue climbing after getting airborne without reducing the pitch angle to gain air- speed. This procedure caused the angle of attack to increase and right wing to stall.

    The second factor was the tip-stalling tendency of the R/STOL kit. The kit incorporates a link between the flaps and ailerons and the ailerons turn downwards in the take off con- figuration. Turning ailerons downwards is unfavorable especially with the aileron mechanism used by Cessna when the hinge line is on the upper surface. Thus turning aileron down causes a sharp angle on the upper surface and induces flow separation. This led to a sudden right wing tip flow separation. The flow separation of a normal standard Cessna aircraft begins from the wing root area, which is favorable and safe.


    The third factor was the wrong action by the pilot to recover from the situation. When the aircraft begun to roll to the right the pilot applied full left aileron and rudder. Probably he did not try to push yoke forward to unstall the wing. The collision with water could probably not have been prevented even with the correct stall recovery actions but the consequences of the collision could have been reduced. The full opposite aileron can also be considered as a wrong action because the right aileron turned downwards and worsened the right wing tip stall. On the other hand, the aileron control must have been a reflex movement for an unexpected roll.

  38. #38
    mvivion's Avatar
    Join Date
    Jun 2003
    Location
    Crookston, MN
    Posts
    7,850
    Post Thanks / Like
    Yep, George--that pretty well says it all. Numbers 1 and 3 that is.

    This information was provided to the US FAA and NTSB, who have taken no action to rescind the Robertson stc. Numbers 1 and 3 are probably a big part of the reason why.

    We ARE expected to actually FLY these things, George.

    MTV

  39. #39
    danfena's Avatar
    Join Date
    Apr 2007
    Location
    Northern MN
    Posts
    88
    Post Thanks / Like
    180 - 185 parts are what I need. If you could do some digging ar a contact that would be great.

  40. #40
    danfena's Avatar
    Join Date
    Apr 2007
    Location
    Northern MN
    Posts
    88
    Post Thanks / Like
    Thanks for the tips, It would be fairly easy to not hook the RStol to the flap belcrank and actuate it by other means. I will consider it.
    It would seem to me that if i where in a cross wind I would use less flaps. The less flaps the less aileron droop. Heck a 180 should land pretty short with no flaps, nose will be high. I do it in my PA-12 because Piper forgot to give me flaps....Ha.........The R/Stol has its place in this world and I like it, after all, any aircraft can and will bite you if you let it. I do have a few hours flying 180, 185, 206 all with Robertson STOL.
    I don't think I have seen a large Boeing or Airbus that doesn't droop every thing it's got. Stol crap comes out of the wing in every direction, only diff I see is they have spoilers to help the roll, like the Helio.
    Parts?? PM me with contacts, thanks.

Similar Threads

  1. Cessna 185 w/robertson stol yarding to the right?
    By pzinck in forum My Other Plane Is A....
    Replies: 3
    Last Post: 09-08-2010, 01:25 AM
  2. C/STOL
    By flyguybri in forum The Art and Science of Flying
    Replies: 1
    Last Post: 06-09-2003, 05:01 PM
  3. Robertson STOL
    By JimC in forum Modifications
    Replies: 0
    Last Post: 02-17-2003, 09:36 AM

Tags for this Thread

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •